More than 30 Cubans, dropped off by a smugglers' speedboat, spent up to eight hours on the off-limits grounds of the Turkey Point nuclear power plant on Thanksgiving Day, then called the plant's nuclear control room to say they were by the cooling canals.

A spokesman for Florida Power & Light said Friday that the group was six miles from the reactors, and the power plant in southern Miami-Dade County ``was not affected in any way.''

But the utility, which boasts of tight security in the area, did not address why its security personnel apparently did not become aware of the Cubans' presence on Turkey Point for up to eight hours.

Information about the incident was revealed by a report that FPL filed with the Nuclear Regulatory Commission, which stated that at 1:28 p.m. Thursday the control room ``received a call from an individual stating that he was a member of a group of Cuban nationals that had landed in the Turkey Point cooling canals.''

FPL has call boxes in the area for use by maintenance workers, a company spokesman said, but it's not clear whether the Cuban used one to call the control room.

Nuclear power plants were directed to sharpen security after the Sept. 11 terrorist attacks. FPL maintains round-the-clock security teams immediately around the Turkey Point plant buildings, which are also protected by several layers of fencing.

The buildings are surrounded by miles of twisting, mangrove-lined canals where hot water discharged from the plant cools as it circulates.

FPL spokesman Michael Waldron said there was no security breach since the Cuban group was nowhere near any of the plant's heavily secured buildings. He did not say how far into the surrounding natural areas the heavy security extends.

``I can tell you that FPL maintains a very strong security program that is regularly evaluated by the federal Nuclear Regulatory Commission,'' Waldron wrote in an e-mail.

``As you know, there are many sensitive aspects of our security program that we cannot discuss in the newspaper, however, these individuals were over six miles from the plant in an environmental area and did not come anywhere near the heavily protected facility.''

According to immigration authorities, the Cubans were dropped off by two smugglers' in a speedboat around 6 a.m. More than seven hours later, the control room learned they were in the cooling canals and called plant security, ``who located and assumed control over the Cuban nationals without incident,'' according to the NRC filing.

FPL security called Miami-Dade police for assistance. Police arrived at 2:25 p.m. and called federal immigration agents, who took the Cubans into custody. The Cubans told agents they were picked up east of Havana by two men in a 30-foot, triple-engine speedboat.

The Cubans were detained 100 feet from the spot where they were dropped, said U.S. Customs and Border Protection spokeswoman Elee Erice. Typically, Cubans detained after reaching U.S. shores are processed and released.

The precise number in the group could not be determined. The NRC put the number at 33, but a Miami-Dade police report had it at 34. The group included four children.

Security at the plant has been managed by Wackenhut, but FPL did not respond to an e-mailed question asking whether the company still does. FPL also did not say who, if anyone, is responsible for safeguarding the canal system.

Earlier this year, FPL paid the NRC a $130,000 fine after an investigation found that six Wackenhut guards slept or acted as lookouts for napping guards while on the job. One guard was ``sleeping while on duty at a post in a vital area of the reactor,'' the NRC said.

In 2005, FPL officials told reporters how they had beefed up security at the plant to guard against terrorist incursions. A small private army armed with automatic weapons patrols the grounds, while bulletproof towers occupy strategic positions to scan the perimeter or lay down crossfire. The plant is ringed with barricades to stop vehicles and fencing to snare intruders.